A genset engine that operates on an open loop EFI system and runs on gaseous fuels is described. The integration of various air sensors, including for example a manifold air temperature (MAT) sensor, a manifold absolute pressure (MAP) sensor, or an air flow sensor(s), can provide optimal engine performance when using gaseous fuels and when starting from a cold state. The sensors employed send data to the electronic control unit (ECU) and such data is used to determine the optimal air-to-fuel ratio (AFR). The ECU actuates the injector and the injector sends the requested amount of gaseous fuel to mix with the air flow to be combusted. This provides the engine with a gaseous fuel and air mixture that is at the requested relative AFR and the engine is able to start and meet performance.